It's been more than 13 years since writer Barbara Ehrenreich went undercover, making beds, cleaning houses, working in the women's-wear department at a Walmart, and opening America's eyes to the bleak realities of our working poor in her groundbreaking Harper's Magazine story, "Nickel-and-Dimed: On (Not) Getting by in America," later expanded into a book by the same title.

Food writer Tracie McMillan has taken Ehrenreich's conceit into the fields of Central California, the produce section of a Detroit-area Walmart and the kitchen of a New York City Applebee's and produced an even more disturbing picture, not only of bleaker realities for today's working poor but also of a national food system dysfunctional at its core: from farm to marketplace to dining table.

McMillan's stint picking grapes, peaches and garlic reveals, not surprisingly to many, an almost entirely immigrant workforce under duress from low wages, few if any health benefits, perilous working conditions and onerous production demands — those same workers, by their often-tenuous legal status, are fearful of protesting their situations.

Meanwhile, in the Walmart produce section where she worked, McMillan witnessed, again, poor wages but also enormous waste — and an absence of the training that might have prevented it — as well as a frightening indifference to sanitation.

Equally unnerving was her experience working in an Applebee's, restaurants being where McMillan says Americans spend 42 percent of their monthly food budget. Again, she received little training in sanitary practices and watched dinners put together from deep fryers, from microwaved foam cups, from ingredients heated in plastic bags, then squeezed onto plates.

"When the kitchen slows down," she writes, "I try, with occasional success, to lure the cooks into talking about food. One assessment is unanimous: We don't cook at Applebee's. We assemble."

McMillan's overarching point here is the disconnect between America's overall wealth and its inability to eat well, best personified by what she calls "food deserts": huge swaths of urban populations, Detroit among them, with little access to full-service grocery stores. The author cites a direct link between a lack of such stores and food-related health problems such as obesity.

How did these food deserts happen?

"Some grocery chains had joined the exodus known as white flight," McMillan writes, "heading for the suburbs after World War II and fleeing in earnest after the urban riots of the 1960s — taking with them all the systems for delivering fruits and vegetables into the neighborhoods. Others simply never planted their flag in urban soil, judging proposals for new stores by their likelihood of success in the suburbs."

If our national food system seems broken, McMillan does offer some hope: the success of an urban-farming program in Detroit, a recent change to allow the use of food stamps in farmer's markets, USDA support of local programs to streamline the logistics of getting food to urban areas, first lady Michelle Obama's achievement in raising the profile of healthy foods.

Maybe the best hope McMillan offers, though, is simply bringing awareness to the problem. Hopefully, a lot of other people will help take it from there.